Electrical diesel particulate filter (DPF) regeneration
An exhaust system that processes exhaust generated by an engine includes a diesel particulate filter (DPF) that is disposed downstream of the engine and that filters particulates from the exhaust. An electrical heater is disposed upstream of the DPF and selectively heats the exhaust to initiate combustion of the particulates within the exhaust as it passes therethrough. Heat generated by combustion of the particulates induces combustion of particulates within the DPF.
The present invention relates to diesel engines, and more particularly to diesel particulate filter (DPF) regeneration.
BACKGROUND OF THE INVENTIONDiesel engines have higher efficiency than gasoline engines due to the increased compression ratio of the diesel combustion process and the higher energy density of diesel fuel. As a result, a diesel engine provides improved gas mileage than an equivalently sized gasoline engine.
The diesel combustion cycle produces particulates that are typically filtered from the exhaust gases. A diesel particulate filter (DPF) is usually disposed along the exhaust stream to filter the diesel particulates from the exhaust. Over time, however, the DPF becomes full and must be regenerated to remove the trapped diesel particulates. During regeneration, the diesel particulates are burned within the DPF to enable the DPF to continue its filtering function.
A traditional regeneration method injects fuel into the exhaust stream after the main combustion event. The post-combustion injected fuel is combusted over catalysts placed in the exhaust stream. The heat released during the fuel combustion on the catalysts increases the exhaust temperature, which burns the trapped soot particles in the DPF. This approach, however, can result in higher temperature excursions than desired, which can be detrimental to exhaust system components including the DPF.
SUMMARY OF THE INVENTIONAccordingly, the present invention provides an exhaust system that processes exhaust generated by an engine. The exhaust system includes a diesel particulate filter (DPF) that is disposed downstream of the engine and that filters particulates from the exhaust. An electrical heater is disposed upstream of the DPF and selectively heats the exhaust to initiate combustion of the particulates within the exhaust as it passes therethrough. Heat generated by combustion of the particulates induces combustion of particulates within the DPF.
In one feature, the electrical heater is offset a distance from the DPF.
In another feature, the electrical heater is a resistive heater.
In still other features, the exhaust system further includes a control module that selectively enables current flow to the electrical heater. The control module determines an estimated amount of particulate matter within the DPF and initiates DPF regeneration when the amount exceeds a threshold amount. The control module enables the current flow for an initial period of a DPF regeneration cycle.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGSThe present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following description of the preferred embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements. As used herein, the term module refers to an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, a combinational logic circuit, or other suitable components that provide the described functionality.
Referring now to
Air is drawn into the intake manifold 14 through a throttle (not shown). Air is drawn into the cylinders 20 from the intake manifold 14 and is compressed therein. Fuel is injected into cylinder 20 by the common rail injection system 16 and the heat of the compressed air ignites the air/fuel mixture. The exhaust gases are exhausted from the cylinders 20 and into the exhaust system 18. In some instances, the diesel engine system 10 can include a turbo 26 that pumps additional air into the cylinders 20 for combustion with the fuel and air drawn in from the intake manifold 14.
The exhaust system 18 includes exhaust manifolds 28,30, exhaust conduits 29,31, a catalyst 38, a diesel particulate filter (DPF) 40 and a heater 41. First and second exhaust segments are defined by the first and second cylinder banks 22,24. The exhaust manifolds 28,30 direct the exhaust segments from the corresponding cylinder banks 22,24 into the exhaust conduits 29,31. The exhaust is directed into the turbo 22 to drive the turbo 22. A combined exhaust stream flows from the turbo 22 through the catalyst 38 and the heater 41 to the DPF 40. The DPF 40 filters particulates from the combined exhaust stream as it flows to the atmosphere. The heater 41 selectively heats the exhaust stream flowing therethrough to regenerate the DPF 40, as explained in further detail below.
A control module 42 regulates operation of the diesel engine system 10 according to the DPF regeneration control of the present invention. More particularly, the control module 42 communicates with an intake manifold absolute pressure (MAP) sensor 44 and an engine speed sensor 46. The MAP sensor 44 generates a signal indicating the air pressure within the intake manifold 14 and the engine speed sensor 46 generates a signal indicating engine speed (RPM). The control module 42 determines an engine load based on the RPM and fueling rates. The fueling rate is generally measured in fuel volume per combustion event. Engine output is controlled via the fueling rate.
With particular reference to
With further reference to
With particular reference to
The DPF regeneration process is periodically initiated to regenerate the DPF 40. More specifically, the control module 42 estimates loading of the DPF. When the estimated loading achieves a threshold level (e.g., 5 grams/liter of particulate matter) and the exhaust flow rate is within a desired range, current is applied to the heater 41 to initiate the regeneration process. The duration of the regeneration process varies based upon the amount of particulate matter within the DPF 40. It is anticipated, that the regeneration process can last between 4-6 minutes. The electrical heater 41, however, is only implemented during an initial portion of the regeneration process. More specifically, the electric heater 41 heats the exhaust flowing therethrough for a threshold period (e.g., 1-2 minutes). The remainder of the regeneration process is achieved using the heat generated by combustion within the DPF 40.
Referring now to
The DPF regeneration system of the present invention provides distinctive advantages over the prior art. More specifically, the DPF regeneration system inhibits extreme temperature excursions that could be detrimental to the exhaust system components. As compared to other electrical energy-based DPF regeneration systems, the DPF regeneration system of the present invention is more efficient (approximately 80-90% efficient).
Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present invention can be implemented in a variety of forms. Therefore, while this invention has been described in connection with particular examples thereof, the true scope of the invention should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, the specification and the following claims.
Claims
1. An exhaust system that processes exhaust generated by an engine, comprising:
- a diesel particulate filter (DPF) that is disposed downstream of the engine and that filters particulates from said exhaust; and
- an electrical heater that is disposed upstream of said DPF and downstream of an oxidizing catalyst, and that selectively heats said exhaust to initiate combustion of said particulates within exhaust as it passes therethrough, wherein heat generated by combustion of said particulates induces combustion of particulates within said DPF; and
- a control module that determines an estimated mass of particulate matter per volume of said DPF and initiates DPF regeneration when said mass of particulate matter per volume of said DPF exceeds a threshold amount.
2. The exhaust system of claim 1 wherein said electrical heater is offset a distance from said DPF.
3. The exhaust system of claim 1 wherein said electrical heater is a resistive heater.
4. (canceled)
5. (canceled)
6. The exhaust system of claim 1 wherein said control module enables said current flow for an initial period of a DPF regeneration cycle.
7. A method of regenerating a diesel particulate filter (DPF) of an exhaust system, comprising:
- generating exhaust including particulates therein;
- determining an estimated mass of particulate matter per volume of said DPF;
- heating said exhaust upstream of said DPF using an electrical heater disposed downstream of an oxidizing catalyst to induce combustion of said particulates when said mass of particulate matter per volume of said DPF exceeds a threshold amount; and
- directing heat generated by combustion of said particulates into said DPF to induce combustion of particulates within said DPF.
8. The method of claim 7 further comprising offsetting said electrical heater a distance from said DPF.
9. The method of claim 7 wherein said electrical heater is a resistive heater.
10. The method of claim 7 wherein said step of heating said exhaust occurs for an initial period of a DPF regeneration cycle.
11. (canceled)
12. A method of regenerating a diesel particulate filter (DPF) of an exhaust system, comprising:
- directing exhaust including particulates through an electrical heater disposed downstream of an oxidizing catalyst;
- determining an estimated mass of particulate matter per volume of said DPF;
- applying current to said electrical heater;
- heating said exhaust upstream of said DPF using said electrical heater to induce combustion of said particulates when said mass of particulate matter per volume of said DPF exceeds a threshold amount; and
- directing heat generated by combustion of said particulates into said DPF to induce combustion of particulates within said DPF.
13. The method of claim 12 further comprising offsetting said electrical heater a distance from said DPF.
14. The method of claim 12 wherein said electrical heater is a resistive heater.
15. The method of claim 12 wherein said step of heating said exhaust occurs for an initial period of a DPF regeneration cycle.
16. (canceled)
Type: Application
Filed: Aug 23, 2005
Publication Date: Mar 1, 2007
Patent Grant number: 8615988
Inventors: Eugene Gonze (Pinckney, MI), Frank Ament (Troy, MI)
Application Number: 11/209,427
International Classification: F01N 3/00 (20060101);